Channel subsystem server time protocol commands

ABSTRACT

A protocol for communicating with the timing facility used in a data processing network to provide synchronization is provided via the execution of a machine instruction that accepts a plurality of commands. The interaction is provided through the use of message request blocks and their associated message response blocks. In this way timing parameters may be determined, modified and communicated. This makes it much easier for multiple servers or nodes in a data processing network to exist as a coordinated timing network and to thus more cooperatively operate on the larger yet identical data files.

This application is a continuation of co-pending, commonly assigned U.S.Ser. No. 13/888,506, entitled “Channel Subsystem Server Time ProtocolCommands,” filed May 7, 2013, which is a continuation of U.S. Pat. No.8,458,361, entitled “Channel Subsystem Server Time Protocol Commands,”issued Jun. 4, 2013, which is a continuation of U.S. Pat. No. 7,689,718,entitled “Channel Subsystem Server Time Protocol Commands and SystemTherefor,” issued Mar. 30, 2010, which claims priority to U.S.Provisional Application No. 60/887,544, entitled “Channel SubsystemServer Time Protocol Commands”, filed Jan. 31, 2007, each of which ishereby incorporated herein by reference in its entirety.

BACKGROUND

The present invention relates in general to timing protocols used indata processing systems which include a plurality of servers, one ormore of which may not be located in the same physical location or whichmay be located some distance apart at a single location. Even moreparticularly, the present invention is directed to a system, method andprogram product which provides a mechanism for communicating with atiming protocol facility in a data processing network.

The present invention is not concerned with networks of data processingservers or nodes whose only function is the carrying out of asynchronouscommunications. Rather, the present invention is directed to multinodedata processing networks which exhibit or require time synchronization.This synchronization is important when it comes to file sharingoperations to insure that the order in which data is read from andwritten into files is consistent with the intentions of system users. Tothis end the assignee of the present invention has provided software andhardware facilities to accomplish these goals. In particular, one mayemploy a device identified as the IBM 9037 Sysplex Timer or ETR(External Time Reference). Because of the high speed of modern dataprocessing systems, timing synchronization is typically set to be suchthat the differences in time lie at the submicrosecond level.

Against these demanding time considerations, it still happens that inthe course of network operation it may become useful or desirable tochange one or more aspect of the timing information that is exchanged inthe network. The changes addressed here are one that are driven byexternal factors, such as the desire of the system operator to changetime zones or the desire to change the timing to account for localvariations and adoptions made for such things as “Daylight SavingsTime.” The communications that are used to match timing information indisparate systems should be reliable.

Use of a time reference such as the 9037 Sysplex Timer, provides thisreliability; the data processing servers in the network thus have adedicated direct connection for the sole purpose of forwarding timinginformation to that system. In this system, directly attached dataprocessing components continually monitor each individual timing relatedinformation field to determine if it has been updated. This involves theuse of processing power at each node in the network to detect changes inthe timing parameters. The timing information typically includes an ETRnetwork identifier, a leap seconds offset and a total time offset, whichis the sum of the time zone and daylight savings time offsets. Scheduledupdates are viewed at the ETR console and not at each individual systemin the timing network. Lastly, if a node loses all communication withthe ETR, the parameter data is considered to be invalid at that point intime.

It is thus seen that it is not only desirable to have the nodes in adata processing network synchronized to a desired degree of accuracy,but that it is also desirable to be able to have a new server join thenetwork in a safe and secure fashion. The process of having a serverleave a network is not as difficult, though it is still important tomaintain synchronization while time dependent processes are running andinteracting with one or more server nodes.

BRIEF SUMMARY

The shortcomings of the prior art are overcome and additional advantagesare provided through the provision of a method of obtaining information.The method includes, for instance, obtaining a store machine instructionfor accessing a first control block of memory and a second control blockof memory, the first control block of memory being a request block andincluding a command code field to specify a store command, and thesecond control block of memory being a response block, the machineinstruction being defined for computer execution according to a computerarchitecture; and executing the machine instruction, the executingincluding, for instance, accessing the command code field of the firstcontrol block to obtain the store command; based on the store command,obtaining information relating to a Server Time Protocol (STP) facility;and storing the information in the second control block.

Computer program products and systems relating to one or more aspects ofthe present invention are also described and may be claimed herein.Further, services relating to one or more aspects of the presentinvention are also described and may be claimed herein.

The recitation herein of a list of desirable objects which are met byvarious embodiments of the present invention is not meant to imply orsuggest that any or all of these objects are present as essentialfeatures, either individually or collectively, in the most generalembodiment of the present invention or in any of its more specificembodiments.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The subject matter which is regarded as the invention is particularlypointed out and distinctly claimed in the concluding portion of thespecification. The invention, however, both as to organization andmethod of practice, together with the further objects and advantagesthereof, may best be understood by reference to the followingdescription taken in connection with the accompanying drawings in which:

FIG. 1 is a block diagram illustrating a useful structure for theCommand-Request Block for the Set STP (Server Time Protocol) Controlscommand;

FIG. 2 is a block diagram illustrating a useful structure for theCommand-Response Block for the Set STP Controls command;

FIG. 3 is a block diagram illustrating a useful structure for theCommand-Request Block for the Store STP Information command;

FIGS. 4A and 4B is a block diagram illustrating a useful structure forthe Command-Response Block for the Store STP Information command;

FIG. 5 is a block diagram illustrating a useful structure for theCommand-Request Block for the Store STP Information Fast command;

FIG. 6 is a block diagram illustrating a useful structure for theCommand-Response Block for the Store STP Information Fast command;

FIG. 7 is a block diagram illustrating a useful structure for theCommand-Request Block for the Store STP Link Information command;

FIG. 8 is a block diagram illustrating a useful structure for theCommand-Response Block for the Store STP Link Information command;

FIG. 9 is a block diagram illustrating a useful structure for theSTP-link-information block that is part of the Command-Response Blockfor the Store STP Link Information command seen in FIG. 8;

FIG. 10 is a block diagram illustrating a useful structure for theCommand-Request Block for the Store STP Network Node Identifierscommand;

FIG. 11 is a block diagram illustrating a useful structure for theCommand-Response Block for the Store STP Network Node Identifierscommand;

FIG. 12 a block diagram illustrating a useful structure for adescription of a Node Information Block;

FIG. 13 is a block diagram illustrating a useful structure for theCommand-Request Block for the Store Time Zone Information command;

FIG. 14 is a block diagram illustrating a useful structure for theCommand Response Block for the Store Time Zone Information command;

FIG. 15 is a block diagram illustrating one of the nodes in which thepresent invention may be employed;

FIG. 16 is a top view of a computer readable medium that is capable ofstoring machine instructions, and source code as well, which implementthe current invention;

FIG. 17 depicts one example of a mixed coordinated timing network toincorporate one or more aspects of the present invention;

FIG. 18 depicts one example of an STP-only network which relates to oneor more aspects of the present invention; and

FIG. 19 is a block diagram illustrating an environment in which theinstructions of the present invention could be emulated.

DETAILED DESCRIPTION

The present application is directed to timing protocols used in dataprocessing systems which employ a plurality of servers, one or more ofwhich may not be located in the same physical location or are locatedsome distance apart at a single location. In particular, the presentinvention involves the inclusion of six new STP commands which operatejointly and severally to improve system timing characteristics. Thesenew commands or “orders” are the following:

-   -   Set STP Controls    -   Store STP Information    -   Store STP Information Fast    -   Store STP Link Information    -   Store STP Network Node Identifiers    -   Store Time Zone Information

STP (Server Time Protocol) messages are transmitted over STP pathsbetween two servers in the form of a message command and a messageresponse. The new commands provided herein are thus described in termsof their effects as initiated via a message request block and as resultin changes in their associated message response blocks. Accordingly, itis seen that much of the discussion below is divided in considerationsconcerning the structure of request and response blocks.

One of these commands is the Set STP Controls command and it isdesignated by the mnemonic “SSTPC.” The Set STP Controls command setscontrol and time information at the STP facility. The Set STP Controlscommand is executed synchronously. These commands, along with theirmnemonics and other relevant properties are summarized in the followingtable:

TABLE I Characteristics Command Name Mnemonic A F I Code Set STPControls SSTPC — — — 0033 Store STP Information SSTPI — — — 0038 StoreSTP Information Fast SSTPF — F I 1040 Store STP Link Information SSTPL —— I 003A Store STP Network Node SSTPN — — I 003C Identifiers Store TimeZone Information STZI — — I 003E

In the table above, the following is the key for the “characteristics”column:

A—The command can be executed asynchronously;

F—The synchronous command is executed quickly;

I—The command can be executed interpretively.

Set STP Controls

The Set STP Controls command uses a control block for purposes ofcommunicating with the STP facility. In particular, it is seen in FIG. 1that bytes 0-1 of word 0 contain the value “0020” hex, specifying acommand-request-block length of 32 bytes. The Command Code is foundwithin bytes 2-3 of word 0 which contains the value “0033” hex,specifying the set-STP-controls command. Places in FIG. 1 that show“Reserved” locations denote areas set aside for other possible futureuses. The field labeled “FMT” in the block of FIG. 1 forms thecommand-request-format field and it contains a 4-bit, unsigned integerwhose value specifies the layout of the command-request block. Byte 0 ofword 2 contains the STP Operation field and contains an operation codedefined as follows:

Code 1: Sync Clock: If the CPC is in the STP-timing mode and theSTP-clock-source state indicates the usable-clock-source state, thesync-clock operation causes the Time of Day (TOD) clock to besynchronized with Coordinated Server Time (CST). The timing state forthe Central Processing Complex (CPC) is set to the synchronized state asa result of the operation. The TOD-clock-change field in the responseblock specifies the amount the TOD clock is modified. If the CPC is notin the STP-timing mode, a response code of “0109” hex applies and theTOD clock is not modified. If the CPC does not have a usable clocksource, a response code of “0108” hex applies and the TOD-clock is alsonot modified.

Code 3: Set-Controls: The set-controls operation sets the STP controlsfor the CPC to the values provided in the STP Controls field in therequest block. The values specified in the STP controls field in therequest block replace the existing settings for the CPC. STP-operationcodes that are not defined are reserved.

STP Controls: When STP operation code 3 is specified in byte 0 of word2, bytes 2-3 of word 2 contain the STP Controls field. Any combinationof defined bits may be set to one and the settings replace the currentsettings for the CPC. When the STP operation code 3 is not specified,the field is ignored. The field is defined as follows.

Bit 0: STP-sync-check control: Bit 0 of the STP controls field, when setto one, enables STP-sync-check machine checks. When set to zero,STP-sync-check machine checks are disabled.

Bit 1: Island-condition control: Bit 1 of the STP controls field, whenset to one, enables island-condition machine checks. When set to zero,island-condition machine checks are disabled.

Bit 2: CTN-configuration-change control: Bit 2 of the STP controlsfield, when set to one, enables CTN-configuration-change machine checks.When set to zero, CTN-configuration-change machine checks are disabled.

Bit 3: STP-clock-source-error control: Bit 3 of the STP controls field,when set to one, enables STP-clock-source-error machine checks. When setto zero, STP-clock-source-error machine checks are disabled.

Bit 8: Timing-status-change-alert control: Bit 8 of the STP controlsfield, when set to one, enables timing-status-change externalinterrupts. When set to zero, timing-status-change external interruptsare disabled.

Bit 9: Link-availability-change-alert control: Bit 9 of the STP controlsfield, when set to one, enables link-availability-change externalinterrupts. When set to zero, link-availability change externalinterrupts are disabled.

Bit 10: Time-control-parameter-alert control: Bit 10 of the STP controlsfield, when set to one, enables time-control-parameter-alert externalinterrupts. When set to zero, STP-time-control parameter-alert externalinterrupts are disabled.

Bits in the STP-controls field that are not defined are reserved. TheSTP-controls field is set to zero as part of a subsystem reset. It isnoted that programs can determine the current sync-check offset byissuing the Store STP Information command. The sync-check amount isstored at words 40-43 of the Store STP Information response block.

Attention is now directed to the structure of a suitable Response Blockfor use with the Set STP Controls command. This block has the structureshown in FIG. 2.

L2: Bytes 0-1 of word 0 specify the length in bytes of thecommand-response block. The length depends on the response code that isstored as a result of the attempt to execute the command. If a responsecode other than “0001” hex is stored in the response-code field, STPcontrol information for the configuration would not have been modifiedas a result of the attempt to execute the command and, in this case, L2specifies a length of eight bytes for the command-response block. If aresponse code of “0001” hex is stored in the response-code field, thespecified STP control information has been set for the configuration asa result of the attempt to execute the command and L2 specifies a lengthof 32 bytes for the command-response block.

Response Code: Bytes 2-3 of word 0 contain a 16-bit unsigned binaryinteger that describes the results of the attempt to execute thecommand.

Reserved: This portion of the block is set aside for possible futureuse.

Format (FMT): Bits 4-7 of word 1 are the command-response-format fieldthat contains a 4 bit, unsigned integer whose value specifies the layoutof the command-response block. The value of the field is set to zero.

TOD Clock Change: When operation code 1 or 4 is set in the STP Operationfield and response code “0001” hex is stored, words 4-5 contain a signedbinary integer indicating the amount that the TOD clock is changed as aresult of the operation. When the value in the STP Operation field isnot equal to 1 or 4, this field is stored as zeros. The stored value hasa resolution equal to TOD-clock bit 63 in current embodiments.

Special Conditions: A special condition exists if a response code otherthan “0001” hex is stored in the command-response block, indicating thatthe execution of the command is suppressed. The special conditions forthe set-STP-Controls command are as follows:

-   -   “0003”: Response code “0003” hex specifies that the L1 field        contains a value other than 0020 hex, a reserved field in the        request block is not zero, or the STP operation code field        specifies a reserved value.    -   “0004”: Response code “0004” hex specifies that the command is        not provided by the model.    -   “0007”: Response code “0007” specifies that the command contains        an invalid FMT value.    -   “0102”: Response code “0102” hex specifies that the command        could not be performed because the STP facility is installed but        is not enabled.    -   “0108”: Response code “0108” hex specifies that the sync-clock        operation is specified and the CPC does not have a valid clock        source.    -   “0109”: Response code “0109” hex specifies that the sync-clock        operation is set and the CPC is not in STP-timing mode.    -   “010A”: Response code “010A” hex specifies that the sync-clock        operation is specified but the clock cannot be synchronized        because the TOD clock is in the stopped state.

Store STP Information

Next is considered the “Store STP Information” command. Thestore-STP-information command returns information about the STP facilityincluding CTN ID, timing status information, time-control parameters andthe current timing parameters that are being used to perform clocksynchronization. The information provided indicates the state of theSTP-facility at the time specified by the data-timestamp field in theresponse block. The store-STP-information command is executedsynchronously. The command-request block has the format shown in FIG. 3.The fields present in this block are specified as follows:

L1: Bytes 0-1 of word 0 contain the value “0010” hex, specifying acommand-request-block length of 16 bytes.

Command Code: Bytes 2-3 of word 0 contain the value “0038” hex,specifying the store STP-information command.

Reserved: This portion of the block is set aside for possible futureuse.

Format (FMT): Bits 4-7 of word 1 are the command-request-format fieldthat contains a 4-bit, unsigned integer whose value specifies the layoutof the command-request block.

The command-response block for the subject command has the format shownin FIGS. 4A and 4B (connected by the arrow shown) and is described asfollows:

L2: Bytes 0-1 of word 0 specify the length in bytes of thecommand-response block. The length depends on the response code that isstored as a result of the attempt to execute the command. If a responsecode other than “0001” hex is stored in the response-code field, no STPinformation has been stored as a result of the attempt to execute thecommand, and L2 specifies a length of eight bytes for thecommand-response block. If a response code of “0001” hex is stored inthe response-code field, STP information has been stored in thecommand-response block and L2 specifies a command-response-block lengthof 384 bytes.

Response Code: Bytes 2-3 of word 0 contain a 16-bit unsigned binaryinteger that describes the results of the attempt to execute thecommand.

Reserved: This portion of the block is set aside for possible futureuse.

Format (FMT): Bits 4-7 of word 1 are the command-response-format fieldthat contains a 4 bit, unsigned integer whose value specifies the layoutof the command-response block.

Time zone Update Scheduled (TU): Bit 0 of word 2, when set to one,indicates that a time zone-update is scheduled. When the bit is set tozero, a time zone-update is not scheduled. The time zone update isspecified by the time zone-control parameters-information block providedin the response block of the store-time zone information command.

Leap Seconds Offset Update Scheduled (LU): Bit 1 of word 2, when set toone, indicates that a leap-seconds-offset-update is scheduled. When thebit is set to zero, a leap-seconds-offset-update is not scheduled. Theleap-seconds-offset-update is specified by theleap-seconds-offset-information block provided in the response block ofthe store-time zone-information command.

Stratum: Bits 8-15 of word 2 contain an unsigned binary integerindicating the stratum level of the CPC at the time the command wasexecuted.

Validity Bits: Bytes 2-3 of word 2 contain validity bits for one or moreof the fields in the response block. When set to one, the bit indicatesthat the specified field is valid. When set to zero, the bit indicatesthat the specified field is invalid. The bits that indicate the validityof response block fields are described below:

TABLE II Bit Field Description 0 Leap Seconds field valid 1 Time ZoneOffset field valid 2 Daylight Savings Time Offset field valid 3 Reserved4 Total Time Offset field valid 5-15 Reserved

Leap Seconds: Bytes 0-1 of word 3, when valid, contain a signed integerindicating the number of leap seconds that are currently in effect forthe CPC.

Timing Mode (TMD): Bits 16-19 of word 3 contain a 4-bit code thatspecifies the timing mode of the CPC. The codes are defined as follows:

TABLE III Code Code Meaning 0 Local Timing Mode 1 ETR Timing Mode 2 STPTiming Mode 3-14 Reserved 15  Uninitialized Timing Mode

CTN Type (CTN): Bits 20-23 of word 3 contain a 4 bit code that specifiesthe type of CTN timing network that is configured at the CPC. The codesare defined as follows:

TABLE IV Code Meaning 0 No CTN defined: the CPC is not configured forattachment to a CTN (that is, an STP network is not defined). The CPC iseither configured for attachment to an ETR-only timing network or to notiming network at all. 1 STP-only CTN: the CPC is configured forattachment to a CTN that does not include an ETR network. 2 Mixed CTN:the CPC is configured for attachment to a CTN that includes an ETRnetwork. 3-15 Reserved.

Local Clock Server (L): Bit 26 of word 3 indicates whether the server ispermitted to act as a local clock server. When the bit is one, theserver can act as a local clock server; when the bit is zero, the servercan not act as a local clock server. This is the “L” part of the fieldlabeled “00LC” in FIG. 4A.

STP Clock Source State (C): Bit 27 of word 3, when set to one, indicatesthat the CPC has a usable clock source. When the bit is zero, the CPCdoes not have a usable clock source. This is the “C” part of the fieldlabeled “00LC” in FIG. 4A.

STP Timing State (TST): Bits 28-31 of word 3 contain a 4-bit code thatspecifies the timing state at the CPC. The codes are defined as follows:

TABLE V Code Meaning 0 Unsynchronized 1 Synchronized with the timingnetwork 2 Physical Clock Stopped 3-15 Reserved

Time Zone Offset: Bytes 0-1 of word 4, when valid, contain a signedbinary integer indicating the time zone difference from UTC currently ineffect at the STP facility. The value is provided in minutes with thelow order bit equaling one minute.

Daylight Savings Time (DST) Offset: Bytes 2-3 of word 4, when valid,contain a signed binary integer indicating the local daylight savingsoffset currently in effect at the STP facility. The value is provided inminutes with the low order bit equaling one minute.

STP Controls: Bytes 0-1 of word 5 contain the current setting of STPControls field and is defined as follows. Bits in the STP-controls fieldthat are not defined are reserved.

TABLE VI Code Meaning 0 STP-sync-check control: Bit 0 of the STPcontrols field, when set to one, indicates STP-sync-check machine checksare enabled. When set to zero, STP-sync-check machine checks aredisabled. 1 Island-condition control: Bit 1 of the STP controls field,when set to one, indicates island-condition machine checks are enabled.When set to zero, island-condition machine checks are disabled. 2CTN-configuration-change: Bit 2 of the STP controls field, when set toone, indicates CTN-configuration-change machine checks are enabled. Whenset to zero, CTN-configuration change machine checks are disabled. 3STP-clock-source-error: Bit 3 of the STP controls field, when set toone, indicates STP-clock-source-error machine checks are enabled. Whenset to zero, STP-clock-source error machine checks are disabled. 8Timing-status-change alert- Bit 8 of the STP controls field, when set toone, indicates timing-status-change external interrupts are enabled.When set to zero, timing-status change external interrupts are disabled.9 Link-availability-change alert: Bit 9 of the STP controls field, whenset to one, indicates link-availability-change external interrupts areenabled. When set to zero, link-availability- change alert externalinterrupts are disabled. 10 Time-control-parameter-alert control: Bit 10of the STP controls field, when set to one, indicatestime-control-parameter-alert external interrupts are enabled. When setto zero, time-control- parameter-alert external interrupts are disabled.

Total Time Offset: Word 6, when valid, indicates the total time offsetthat is in effect at the STP facility. It is the combination of thedaylight savings time and time zone adjustments that are in effect atthe CPC. When the DST-offset field and the time zone-offset are valid,the field is equal to the sum of these fields. When one or both of thesefields are not valid, the total-time-offset field indicates an offsetthat is provided to the STP facility without specifying individually theDST-offset and time zone-offset fields. The value is provided in minuteswith the low order bit equaling one minute.

Maximum Timing Stratum Level: Byte 0 of word 7 contains a 1-byteunsigned binary integer that specifies the maximum stratum level that aserver can be set at and be in the synchronized state. A server with astratum level greater than the maximum-timing-stratum level is in theunsynchronized timing state and the not-usable clock source state.

Maximum Stratum Level: Byte 1 of word 7 contains a 1-byte unsignedbinary integer that specifies the maximum stratum level that can be setfor any server in the CTN.

Maximum Version: Byte 2 of word 7 contains a 1-byte unsigned binaryinteger from 0-255 that indicates the maximum STP version numbersupported by the CPC with zero being lowest and 255 being the highestpossible version supported.

Active Version: Byte 3 of word 7 contains a 1 byte unsigned binaryinteger in the range of 0 to the value in the maximum-version field thatindicates the STP version number that is currently active at the CPC.

CTN ID: Words 8-10 contain the 12-byte CTN ID for the CPC and has thefollowing format:

TABLE VII STP Network ID ETR Network Number

STP Network ID: Bytes 0-7 of the CTN ID identify the STP network, ifany, that is configured for the CPC. The values for this field aredefined as follows:

TABLE VIII Hex Value Meaning 0000 0000 0000 0000 Null - the server isnot configured to be part of a CTN 0000 0000 0000 0001 - The server isconfigured to be part of a CTN. FFFF FFFF FFFF FFEF The value identifiesthe STP network for the CTN. FFFF FFFF FFFF FFF0- Reserved FFFF FFFFFFFF FFFF

ETR Network Number: Bytes 8-11 of the CTN ID identify the ETR networknumber that is configured for the CPC. The field is defined as follows:

TABLE IX Zeros ETR Net ID

ETR Net ID: Bits 24-31 of the ETR Network Number identify the ETRnetwork, if any, that is configured for the CPC. The values for thisfield are defined as follows:

TABLE X Hex Value Meaning 00-1F The CPC is configured for attachment toan ETR network that is identified by this value. 20-FE Reserved FF TheCPC is not configured for attachment to an ETR network.

TOD-Clock Offset: Words 12-13 contain the TOD-clock offset value for theserver. Bit 63 has a resolution equal to that of bit 63 of the TODclock.

CST Offset: Words 16-17 contain the difference between the TOD clock andthe Coordinated Server Time (CST) for the timing network. Bit 63 has aresolution equal to that of bit 63 of the TOD clock. For stratum-1 andstratum-0 servers, this field is set to zero.

CST Route Delay: Words 20-21 contain a 64-bit signed binary integerindicating the total roundtrip message delay to the selected stratum-1server from this server. Bit 63 has a resolution equal to that of bit 63of the TOD clock. For stratum-1 and stratum-0 servers, this field is setto zero.

CST Dispersion: Words 22-23 contain a 64-bit unsigned binary integerindicating the dispersion of CST. Bit 63 has a resolution equal to thatof bit 63 of the TOD clock.

Maximum Skew Rate: Word 24 contains an unsigned 32-bit binary numberthat specifies the absolute value of the unknown skew rate of the TODclock at a secondary server relative to the stratum-1 server selected asthe root clock source. The value is equal to the maximum oscillatorfrequency skew and, in an STP-only CTN, the maximum unrecognized primaryreference time (PRT) correction that can occur. The value has aresolution of one part per 244.

CST Reference Timestamp: Words 28-29 contain the timestamp indicatingwhen the CST offset reported in words 16-17 was updated. For stratum1and stratum-0 servers, the field is set to zero. The field is inSTP-timestamp format.

CST Reference Identifier: Words 32-39 contain a 32-byte value thatidentifies the source of the reference time for the server. Forstratum-1 servers, it identifies the type of primary-reference timesource in the form of a left-justified 4-byte EBCDIC code; for secondaryservers it contains the node descriptor of the CPC selected to provideCST. The field has the following values for stratum-1 servers:

TABLE XI Code Meaning CPPS Console PPS time service CDTS Console dial-uptime service CMAN Console manually set time CGPS Console GPS connectionCNTP Console using NTP ETRS ETR-9037 stepping connection PPSC Directattach PPS with console as reference source. DETS Direct attach ETS DGPSDirect attach GPS ETRN ETR-9037 providing a primary reference

Sync-Check Offset: Words 40-43 contain the sync-check offset for theguest issuing the operation. The field is in extended-TOD-clock format.

Data Timestamp: Words 44-45 contain bits 0-63 of the TOD clock at thetime the data in the response area was stored.

Stratum-1 Configuration Information Block: Words 48-74 contain thestratum-1-configuration information block (SCIB) for the CPC. When theserver is configured to be part of an STP-only CTN, the block containsthe stratum-1 configuration for the STP-only CTN. When the CPC is notconfigured to be part of an STP-only CTN, the field is meaningless.

PRT Correction Steering Information Block: Words 80-95 contain theprimary-reference-time correction-steering-information block (PCSIB).When the CPC is configured to be part of an STP-only CTN, the blockcontains information regarding the primary-reference time for the CTN.When the CPC is not configured to be part of an STP-only CTN, the fieldis meaningless.

Special Conditions: A special condition exists if a response code otherthan “0001” hex is stored in the command-response block, indicating thatthe execution of the command is suppressed. The special conditions forthe store-STP-information command are as follows:

TABLE XII Code Meaning “0003” Response code “0003” hex specifies thatthe L1 field contains a value other than 0010 hex or a reserved field inthe request block is not zero. “0004” Response code “0004” hex specifiesthat the command is not provided by the model. “0007” Response code“0007” hex specifies that the command specifies an invalid format.“0102” Response code “0102” hex specifies that the command could not beperformed because the STP facility is installed but is not enabled.

Store STP Information Fast

Next is considered the Store STP Information Fast command. Thestore-STP-information-fast command returns information about the STPfacility including the CTN ID and the timing state. The informationreturned is a subset of the information provided by the Store STPInformation command. The store-STP-information-fast command is executedsynchronously and can be interpretively executed using the SIE facility.The command-request block for this command has the format shown in FIG.5.

L1: Bytes 0-1 of word 0 contain the value “0010” hex, specifying acommand-request-block length of 16 bytes.

Command Code: Bytes 2-3 of word 0 contain the value “1040” hex,specifying the store-STP information-fast command.

Reserved: The fields so labeled are set aside for possible future use.

Format (FMT): Bits 4-7 of word 1 are the command-request-format fieldthat contains a 4-bit, unsigned integer whose value specifies the layoutof the command-request block.

Attention is now directed to the structure of the Command-Response Blockfor the Store STP Information Fast command. This structure isillustrated in FIG. 6. The following fields and their uses are describedbelow:

L2: Bytes 0-1 of word 0 specify the length in bytes of thecommand-response block. The length depends on the response code that isstored as a result of the attempt to execute the command. If a responsecode other than “0001” hex is stored in the response-code field, no STPinformation has been stored as a result of the attempt to execute thecommand, and L2 specifies a length of eight bytes for thecommand-response block. If a response code of “0001” hex is stored inthe response-code field, STP information has been stored in thecommand-response block and L2 specifies a command-response-block lengthof 64 bytes.

Response Code: Bytes 2-3 of word 0 contain a 16-bit unsigned binaryinteger that describes the results of the attempt to execute thecommand.

Reserved: All fields so labeled are set aside for possible future use;all such fields may be provided with a default value for convenience.All such fields in this block are served by this description.

Format (FMT): Bits 4-7 of word 1 are the command-response-format fieldthat contains a 4 bit, unsigned integer whose value specifies the layoutof the command-response block.

Timing Mode (TMD): Bits 16-19 of word 3 contain a 4-bit code thatspecifies the timing mode of the CPC. The codes are defined as follows:

TABLE XIII Code Meaning 0 Local Timing Mode 1 ETR Timing Mode 2 STPTiming Mode 3-14 Reserved 15  Uninitialized Timing Mode

Timing State (TST): Bits 28-31 of word 3 contain a 4-bit code thatspecifies the timing state of the system TOD clock. The codes aredefined as follows:

TABLE XIV Code Meaning 0 Unsynchronized 1 Synchronized with the timingnetwork 2 Physical Clock Stopped 3-15 Reserved

CTN ID: Words 8-10 contain the 12-byte CTN ID for the CPC.

Special Conditions: A special condition exists if a response code otherthan “0001” hex is stored in the command-response block, indicating thatthe execution of the command is suppressed. The special conditions forthe store-STP-information-fast command are as follows:

-   -   “0003”: Response code “0003” hex specifies that the L1 field        contains a value other than “0010” hex or a reserved field in        the request block is not zero.    -   “0004”: Response code “0004” hex specifies that the command is        not provided by the model.    -   “0007”: Response code “0007” hex specifies that the command        contains an invalid format.    -   “0102”: Response code “0102” hex specifies that the command        could not be performed because the STP facility is installed but        is not enabled.

Store STP Link Information

Attention is now directed to the Store STP Link Information command andthe description of its Request and Response blocks. The store-STP-linkinformation command is used to store link information for each link atthe CPC that is capable of supporting STP message communication. Thestore-STP-link information command is executed synchronously. Thecommand-request block has the format shown in FIG. 7.

L1: Bytes 0-1 of word 0 contain the value “0010” hex, specifying acommand-request-block length of 16 bytes.

Command Code: Bytes 2-3 of word 0 contain the value “003A” hex,specifying the store-STP-link information command.

Reserved: set aside for possible future use.

Format (FMT): Bits 4-7 of word 1 form the command-request-format fieldthat contains a 4-bit, unsigned integer whose value specifies the layoutof the command-request block.

Token: Word 2 contains a 32-bit unsigned binary integer that, whennon-zero, requests that additional link-information blocks be stored.The token may be set to a non-zero value when the response block fromthe immediately previous store-STP-link-information command issued fromthis configuration contained a non-zero token. A non-zero token in aresponse block indicates that additional link-information blocks wereavailable and, when the token is set in the next request, additionallink information blocks will be provided in the response block. Thetoken field is set to zero when the request is not for additionalblocks.

Next is considered the Response Block for the Store STP Link Informationcommand. The structure of this block is set out in FIG. 8. The fieldsemployed and their meanings are as follows:

L2: Bytes 0-1 of word 0 specify the length in bytes of thecommand-response block. The length depends on the response code that isstored as a result of the attempt to execute command. If a response codeother than “0001” hex is stored in the response-code field, nolink-information blocks are stored as a result of the attempt to executethe command, and L2 specifies a length of eight bytes for thecommand-response block. If a response code of “0001” hex is stored inthe response-code field, one or more STP link-information blocks arestored in the command-response block. L2 specifies acommand-response-block length of 112 bytes plus 128 bytes for each STPlink-information block that is stored. The program can determine thenumber of STP link-information blocks that are stored by subtracting 112from the size of the command-response block and dividing the remainderby 128.

Response Code: Bytes 2-3 of word 0 contain a 16-bit unsigned binaryinteger that describes the results of the attempt to execute thecommand.

Reserved: Set aside for possible future use as described above(applicable to all such fields in this block and elsewhere herein).

Format (FMT): Bits 4-7 of word 1 form the command-response-format fieldthat contains a 4 bit, unsigned integer whose value specifies the layoutof the command-response block.

Token: Word 2 contains a 32-bit unsigned binary integer that indicateswhether additional, unread link-information blocks remain at the STPfacility. A value of zero indicates that no additional, unreadlink-information blocks remain at the STP facility. A non-zero valueindicates additional, unread link-information blocks are available atthe STP facility and that the token, when set in the next store-STPlink-Information command issued from this configuration, will retrieveadditional link-information blocks. The token is valid only for nextStore STP Link Information issued from the configuration.

Words 28-n: If a response code of “0001” hex is stored in theresponse-code field, up to 31,128 byte STP link-information blocks arestored in words 28-n. STP-Link-information blocks are stored for allSTP-capable links. Link-information blocks are not stored for physicalchannels that are not capable of supporting STP messaging. EachSTP-link-information block has the structure that is shown in FIG. 9.

STP-Link Identifier (SLID): Bytes 0-1 of word 0 contains the identifierfor the STP link being described by this STP link-information block.Each STP-capable link in a CPC has a unique SLID that is assigned by theSTP facility.

DESC: Byte 2 of word 0 contains a code which describes the STP-link typefor the link being described by this link-information block. The codesare defined as follows:

TABLE XV Code Meaning 00 Reserved 01 Coupling-peer link 02 Infinibandlink 03-FF Reserved

Initialized (I): Bit 24 of word 0, when set to one indicates that theSTP path is in the STP initialized state and is available for STPmessaging. When the bit is zero, the STP path is in the STPuninitialized state. The uninitialized reason code in bits 28-31 of word0 specifies the reason that the path is uninitialized.

Uninitialized Reason Code (URC): Bits 27-31 of word 0 are valid when theSTP path for this link is in the uninitialized state and contain a 5-bitcode that indicates the reason that the path is in the uninitializedstate. The codes are defined below in Table XVI and are in order ofdecreasing priority. The code stored for a path represents the mostrecent condition recognized for the path. When multiple conditions canbe detected concurrently, the higher priority condition is reported.Unspecified codes for the URC field are reserved.

TABLE XVI Hex Code Meaning 0 Offline: the physical link is in theoffline state. A link in the offline state can not be initialized forSTP communication and is considered not operational. 1 InitializationNot Complete: the physical link is operational but path initializationhas not been attempted or is in progress but has not entered states X’E’or X’F’. 2 Link Failure: a link failure has been detected on thephysical link. A link in the link-failure state can not be initializedfor STP communication and is considered not operational. 3 Fenced: thelink is operational but has been put into the fenced state and can notbe initialized. A link in the fenced state can not be initialized forSTP communication and is considered not operational. 4 Incoming ESPCommand Reject: the server responded to an ESP message command with aresponse code other than 0001 hex. The response code sent to theattached server is stored in byte 0 of word 1. 5 Outgoing ESP CommandReject: the server received a response code of other than 0001 hex to anESP message command. The response code that was received from theattached server is stored in byte 0 of word 1. 6 Communication Error: acommunication error has been recognized for the attached serverindicating that the attached server has not communicated with thisserver for a period greater than the freewheel period. 7 ConfigurationError: a configuration error has been recognized for the attached serverindicating the attached server has provided a mismatched CTN ID on oneof the paths to the attached server. 8 Removed Path: a remove-STP-pathcommand has been received from the attached server. D No Response: anESP command has been attempted but did not receive a response within themessage timeout period. E Incoming ESP Command Pending: the server hasreceived a response code of 0001 hex for an ESP command sent to theattached node and is waiting for an ESP command from the node tocomplete the path initialization process. F Outgoing ESP CommandPending: the server has responded with a response code of 0001 hex to anESP command from the attached node and must send an ESP command to thenode to complete the path initialization process.

Establish STP Path (ESP) Response Code: Byte 0 of word 1 contains an ESPresponse code when the URC contains code 4 or 5.

Stratum Level: Byte 1 of word 1 contains the stratum level of theattached server.

Attached CTN ID: Words 2-4 contain the CTN ID of the attached CPC asreported by the attached CPC on the STP link. The field contains validdata when the I bit equals one or the URC field contains a value of 5.

Link Node Descriptor: The link node descriptor contains a CPC-type nodedescriptor of the link being identified by this link-information block.

Attached Node Descriptor: The attached-node descriptor contains aCPC-type node descriptor of the node attached to the STP link.

Special Conditions: A special condition exists if a response code otherthan “0001” hex is stored in the command-response block, indicating thatthe execution of the command is suppressed. The special conditions forthe store-STP-link-information command are as follows:

-   -   “0003”: Response code “0003” hex specifies that the L1 field        contains a value other than “0020” hex or a reserved field in        the request block is not zero.    -   “0004”: Response code “0004” hex specifies that the command is        not provided by the model.    -   “0007”: Response code “0007” hex specifies that the command        specifies an invalid format.    -   “0102”: Response code “0102” hex specifies that the command        could not be performed because the STP facility is installed but        is not enabled.

Store STP Network Node Identifiers

Attention is now directed to a description of the Store STP Network NodeIdentifiers command and its corresponding Request and Response Blocks.The store-STP-network-node-identifiers command is used to store nodeidentification information for nodes in the STP network to which thisCPC belongs. The execution of the store-STP-network node-identifierscommand does not change any information contained in the channelsubsystem. The information provided in node descriptors is maintained bythe STP facility and does not require an access to the STP network atthe time of the command. The store-STP-network-node-identifiers commandis executed synchronously. The command-request block has the formatshown in FIG. 10. The structure, content and meaning of the variousfields employed are shown below.

L1: Bytes 0-1 of word 0 contain the value “0040” hex, specifying acommand-request-block length of 64 bytes.

Command Code: Bytes 2-3 of word 0 contain the value “003C” hex,specifying the store-STP-network node-identifier command.

Node Selector (NS): Bits 0-1 word 1, contain a value that specifies thetype of node that is to be identified. The meaning or each value is asfollows:

-   -   0: All nodes in the STP network that are attached to the node        receiving the Store STP-network-node-identifiers command are to        be identified.        When this NS is specified, the node descriptor in the request        block has no meaning and is ignored. Node-selector codes that        are not defined are reserved.

Reserved: Set side for future use as described above.

Format (FMT): Bits 4-7 of word 1 are the command-request-format fieldthat contains a 4-bit, unsigned integer whose value specifies the layoutof the command-request block.

Token: Word 2 contains a 32-bit unsigned binary integer that, whennon-zero, requests that additional node-information blocks be stored.The token may be set to a non-zero value when the response block fromthe immediately previous store-STP-network-node-identifiers commandissued from this configuration contained a non-zero token. A non-zerotoken in a response block indicates that additional node-informationblocks were available and, when the token is set in the next request,additional node-information blocks will be provided in the responseblock. The token field is set to zero when the request is not foradditional blocks.

Next is considered the Response Block that is employed with the StoreSTP Network Node Identifiers command. Its structure is set forth in FIG.11. The structure, content and meaning of the various fields employedare shown below:

L2: Bytes 0-1 of word 0 specify the length in bytes of thecommand-response block. The length depends on the response code that isstored as a result of the attempt to execute the command. If a responsecode other than “0001” hex is stored in the response-code field, no nodedescriptors are stored as a result of the attempt to execute thecommand, and L2 specifies a length of eight bytes for thecommand-response block. If a response code of “0001” hex is stored inthe response-code field, one or more node descriptors are stored in thecommand-response block. L2 specifies a command-response-block length of16 bytes plus 32 bytes for each node descriptor that is stored. Theprogram can determine the number of node descriptors that are stored bysubtracting 16 from the size of the command-response block and dividingthe remainder by 32.

Response Code: Bytes 2-3 of word 0 contain a 16-bit unsigned binaryinteger that describes the results of the attempt to execute thecommand.

Reserved: All fields so designated are set aside for possible futureuse.

Format (FMT): Bits 4-7 of word 1 form the command-response-format fieldthat contains a 4 bit, unsigned integer whose value specifies the layoutof the command-response block.

Token: Word 2 contains a 32-bit unsigned binary integer that indicateswhether additional, unread node-information blocks remain at the STPfacility. A value of zero indicates that no additional, unreadnode-information blocks remain at the STP facility. A non-zero valueindicates additional, unread node-information blocks are available atthe STP facility and that the token, when set in the nextstore-STP-network-node-identifiers command issued from thisconfiguration, retrieves additional node-information blocks. The tokenis valid only for next store-STP-network-node-identifiers command issuedfrom the configuration.

Node Information Blocks: If a response code of “0001” hex is stored inthe response-code field, up to 62, 64-byte node-information blocks arestored in the fields shown. If all requested node-information blockscould not be stored in the response block, the token field in word 2 ofthe response block contains a token that can be provided on a subsequentrequest to obtain additional node-information blocks. Eachnode-information block has the format shown in FIG. 12. The structure,content and meaning of the various fields employed are shown below:

Node Descriptor: Words 0-7 of each node-information block contains aCPC-type node descriptor of a node in the STP network.

Flags: Byte 0 in word 8 contains the flags field and is defined asfollows:

TABLE XVI Bit Meaning 0 Attached Server -bit 0, when one, indicates theserver described by the node descriptor is directly attached to thisserver. 1 Reporting Server -bit 1, when one, indicates the serverdescribed by this node descriptor is the server providing thenetwork-node list. 2-7 Reserved

Stratum Level: Byte 1 of word 8 contains the stratum level of theserver.

Reserved: Set side for future use as described above.

Special Conditions: A special condition exists if a response code otherthan “0001” hex is stored in the command-response block, indicating thatthe execution of the command is suppressed. The special conditions forthe store-STP-network-node command are as follows:

-   -   “0003”: Response code “0003” hex specifies that the L1 field        contains a value other than 0040 hex or a reserved field in the        request block is not zero.    -   “0004”: Response code “0004” hex specifies that the command is        not provided by the model.    -   0007”: Response code “0007” hex specifies that the command        specifies an invalid format.    -   “0102”: Response code “0102” hex specifies that the command        could not be performed because the STP facility is installed but        is not enabled.

Store Time Zone Information

Attention is now directed to a description of the Store Time ZoneInformation command and its corresponding Request and Response Blocks.The Store Time Zone Information command is used to store the time zonecontrol parameters and leap-seconds offset information for the CPC. Theinformation provided indicates the state of the STP-facility at the timespecified by the data-timestamp field in the response block. The StoreTime Zone Information command is executed synchronously. Thecommand-request block has the format shown in FIG. 13. The structure,content and meaning of the various fields employed are shown below.

L1: Bytes 0-1 of word 0 contain the value “0010” hex, specifying acommand-request-block length of 16 bytes.

Command Code: Bytes 2-3 of word 0 contain the value “003E” hex,specifying the Store Time Zone Information command.

Reserved: Set aside for possible future use as discussed above.

Format (FMT): Bits 4-7 of word 1 form the command-request-format fieldthat contains a 4-bit, unsigned integer whose value specifies the layoutof the command-request block.

The command-response block for this command has the format shown in FIG.14. The structure, content and meaning of the various fields employedare shown below.

L2: Bytes 0-1 of word 0 specify the length in bytes of thecommand-response block. The length depends on the response code that isstored as a result of the attempt to execute command. If a response codeother than “0001” hex is stored in the response-code field, no time zoneinformation was stored as a result of the attempt to execute thecommand, and L2 specifies a length of eight bytes for thecommand-response block. If a response code of “0001” hex is stored inthe response-code field, L2 specifies a command-response-block length of124 bytes.

Response Code: Bytes 2-3 of word 0 contain a 16-bit unsigned binaryinteger that describes the results of the attempt to execute thecommand.

Reserved: Set aside for possible future use as discussed above. This isapplicable to all of the similarly labeled fields in this block.

Format (FMT): Bits 4-7 of word 1 form the command-response-format fieldthat contains a 4 bit, unsigned integer whose value specifies the layoutof the command-response block.

Data Timestamp: Words 4-5 contain bits 0-63 of the TOD clock at the timethe data in the response area was stored.

Time zone Control Parameters Information Block (TCPIB): Words 28-51contain the TCPIB for the CPC.

Leap Seconds Offset Information Block (LSOIB): Words 52-55 contain theLSOIB for the CPC.

Special Conditions: A special condition exists if a response code otherthan “0001” hex is stored in the command-response block, indicating thatthe execution of the command is suppressed. The special conditions forthe Store Time Zone Information command are as follows:

-   -   “0003”: Response code 0003 hex specifies that the L1 field        contains a value other than “0010” hex or a reserved field in        the request block is not zero.    -   “0004”: Response code “0004” hex specifies that the command is        not provided by the model.    -   “0007”: Response code “0007” hex specifies that the command        specifies an invalid format.    -   “0102”: Response code “0102” hex specifies that the command        could not be performed because the STP facility is installed but        is not enabled.

The Store-Channel-Subsystem-Characteristics command is modified toinclude the following definitions in the general characteristics field:

-   -   Bit 68: The Server Time Protocol (STP) facility is installed.        The STP-facility-enabled bit (bit 69) in the channel-subsystem        general characteristics field is equal to one for the STP        facility to be operational.    -   Bit 69: The Server Time Protocol (STP) facility is enabled. Bit        69 is meaningful only when the STP-facility-installed bit (bit        68) is one. When bits 68 and 69 are both one, the STP facility        is operational. When bit 68 is one and bit 69 is zero, the STP        facility is not operational and commands associated with the STP        facility return a response code of “0102” hex.

The STP facility is enabled by manual means (for example, via operatorcontrols) and, when enabled, the facility is placed into the operationalstate and bit 69 is stored as one when the store-channel-subsystemcharacteristics command is executed.

The STP-enabled characteristic is maintained through a power-on reset,Once the STP facility-enabled is set to ne, the facility can only bedisabled while the machine is in the power-off state.

SCLP Information: The sync-check-threshold field defined at bytes120-127 of the SCCB returned by the Read SCP Information command isremoved and the SCCB is not used by the STP facility.

The description above sets forth the structure of various blocks andfields within these blocks in terms of their sizes and positions. Allsuch size and position parameters are mere design choices with the fieldsizes selected to be long enough to contain and to delineate theprescribed meanings Positions within blocks are fundamentally arbitrarychoices selected for convenience and consistency. Neither field size notfield position within a block is considered to be a limitation on thescope of the invention or on the claims which describe it.

In any event one of the environments in which the present inventionoperates is shown in FIG. 15. The present invention operates in a dataprocessing environment which effectively includes one or more of thecomputer elements shown in FIG. 15. In particular, computer 500 includescentral processing unit (CPU) 520 which accesses programs and datastored within random access memory 510. Memory 510 is typically volatilein nature and accordingly such systems are provided with nonvolatilememory typically in the form of rotatable magnetic memory 540. Whilememory 540 is preferably a nonvolatile magnetic device, other media maybe employed. CPU 530 communicates with users at consoles such asterminal 550 through Input/Output unit 530. Terminal 550 is typicallyone of many, if not thousands, of consoles in communication withcomputer 500 through one or more I/O unit 530. In particular, consoleunit 550 is shown as having included therein a device for reading mediumof one or more types such as CD-ROM 600 shown in FIG. 16. Media 600, anexample of which is shown in FIG. 4, comprises any convenient deviceincluding, but not limited to, magnetic media, optical storage devicesand chips such as flash memory devices or so-called thumb drives. Disk600 also represents a more generic distribution medium in the form ofelectrical signals used to transmit data bits which represent codes forthe instructions discussed herein. While such transmitted signals may beephemeral in nature they still, nonetheless constitute a physical mediumcarrying the coded instruction bits and are intended for permanentcapture at the signal's destination or destinations.

One example of a mixed CTN configuration 100 is described with referenceto FIG. 17. Mixed CTN configuration 100 includes, for instance, Server A(102) coupled to a local area network (104), Server B (106) coupled tolocal area network (104) and Server C (108) coupled to a local areanetwork (110). Each server is, for instance, a central processingcomplex based on the z/Architecture® of International Business MachinesCorporation. z/Architecture® is a registered trademark of InternationalBusiness Machines Corporation, Armonk, N.Y., USA. One embodiment of thez/Architecture® is described in “z/Architecture Principles ofOperation,” IBM Publication No. SA22-7832-04, September 2005.

Each local area network is coupled to a console 120 used in providingtime synchronization within the network. Further, local area network 104and local area network 110 are coupled to one another via a wide areanetwork 112.

Servers A and B are coupled to an external time reference network 114,and Servers B and C are configured to be part of an STP network 116.Server B is at a stratum-1 level and Server C is at a stratum-2 level.STP links 118 are used to couple the STP facility of Server B with theSTP facility of Server C.

In an STP-only CTN, the servers in the CTN are configured to be part ofan STP network and none are configured to be part of an ETR network. Oneexample of a STP-only network 150 is described with reference to FIG.1B. In this example, Server A (152) and Server B (154) are coupled to aLAN (156), and Server 5 (158) is coupled to a LAN (160). Each of theservers includes an STP facility 162, and each facility is coupled toone another via one or more STP links 164.

Further, LAN 156 is coupled to a console 170 and LAN 160 is coupled to aconsole 172. Console 170 is further coupled to external time source(ETS) 174. In this network, there is no ETR network. Server B has astratum level of 1, and Servers A and C have a stratum level of 2.

It is noted that instructions like the ones described herein are alsocapable of being emulated. The typical emulation environment in whichthe present invention could be exploited is illustrated in FIG. 19.Emulators such as 320 except as input instruction streams 305,representing machine or assembly language instructions which aredesigned to operate on source machine 300. Emulator 320 employs memory315 in target machine 310 to produce a stream of instructions which arecapable of executing on target machine 310. While FIG. 19 particularlyshows operation within an emulation environment, it is also noted thatthe present invention contemplates a situation in which emulator 320operates essentially as an interpreter in which the instructions are notonly translated to the new architecture but in which they are alsoexecuted at essentially the same time.

Additional information regarding timing networks is provided in thefollowing patent applications, each of which is hereby incorporatedherein by reference in its entirety: U.S. Provisional Ser. No.60/887,584 entitled “Facilitating Synchronization Of Servers In ACoordinated Timing Network”, filed Jan. 31, 2007; U.S. Ser. No.11/876,152 entitled “Facilitating Synchronization Of Servers In ACoordinated Timing Network”, filed Oct. 22, 2007; U.S. Ser. No.11/876,199 entitled “Definition Of A Primary Active Server In ACoordinated Timing Network”, filed Oct. 22, 2007; U.S. Provisional Ser.No. 60/887,562 entitled “Defining A Stratum-1 Configuration In ACoordinated Timing Network”, filed Jan. 31, 2007; U.S. Ser. No.11/876,240 entitled “Employing Configuration Information To DetermineThe Role Of A Server In A Coordinated Timing Network”, filed Oct. 22,2007; U.S. Provisional Ser. No. 60/887,576 entitled “Method And SystemFor Establishing A Logical Path Between Servers In A Coordinated TimingNetwork”, filed Jan. 31, 2007; U.S. Ser. No. 11/876,272 entitled“Establishing A Logical Path Between Servers In A Coordinated TimingNetwork”, filed Oct. 22, 2007; U.S. Provisional Ser. No. 60/887,586entitled “Facilitating Recovery In A Coordinated Timing Network”, filedJan. 31, 2007; U.S. Ser. No. 11/876,323 entitled “Facilitating RecoveryIn A Coordinated Timing Network”, filed Oct. 22, 2007; U.S. ProvisionalSer. No. 60/887,544 entitled “Channel Subsystem Server Time ProtocolCommands”, filed Jan. 31, 2007; U.S. Provisional Ser. No. 60/887,512entitled “Server Time Protocol Messages And Methods”, filed Jan. 31,2007; U.S. Ser. No. 11/468,352, entitled “Coordinated Timing NetworkConfiguration Parameter Update Procedure,” filed Aug. 30, 2006; U.S.Pat. No. 7,395,448 entitled “Directly Obtaining By Application ProgramsInformation Usable In Determining Clock Accuracy”, issued Jul. 1, 2008;U.S. Pat. No. 7,356,725 entitled “System And Method For TOD-ClockSteering”, issued Apr. 8, 2008; U.S. Ser. No. 11/532,168 entitled“Synchronization Signal For TOD-Clock Steering Adjustment”, filed Sep.15, 2006; U.S. Ser. No. 11/468,501 entitled “Managing Data Access Via ALoop Only If Changed Locking Facility”, filed Aug. 30, 2006; U.S. Ser.No. 11/223,878 entitled “Clock Filter Dispersion”, filed Sep. 9, 2005;U.S. Ser. No. 11/223,876 entitled “Method And System For Clock Skew AndOffset Estimation”, filed Sep. 9, 2005; U.S. Pat. No. 7,475,272 entitled“Method For Calculation Clock Offset And Skew”, issued Jan. 6, 2009; andU.S. Pat. No. 7,454,648 entitled “System And Method For Calibrating ATime Of Day Clock In A Computing System Node Provided In A Multi NodeNetwork”, issued Nov. 18, 2008.

While the invention has been described in detail herein in accordancewith certain preferred embodiments thereof, many modifications andchanges therein may be effected by those skilled in the art.Accordingly, it is intended by the appended claims to cover all suchmodifications and changes as fall within the true spirit and scope ofthe invention.

What is claimed is:
 1. A method of obtaining information, said methodcomprising: obtaining a store machine instruction for accessing a firstcontrol block of memory and a second control block of memory, the firstcontrol block of memory being a request block and including a commandcode field to specify a store command, and the second control block ofmemory being a response block, the machine instruction being defined forcomputer execution according to a computer architecture; and executingsaid machine instruction, said executing comprising: accessing saidcommand code field of said first control block to obtain said storecommand; based on the store command, obtaining information relating to aServer Time Protocol (STP) facility; and storing said information in thesecond control block.
 2. The method of claim 1, wherein the informationindicates a state of the STP facility at a time specified by adate-timestamp field of the response block.
 3. The method of claim 1,wherein the store command comprises a store STP information command, andwherein the information includes at least one of a coordinated timingnetwork identifier, timing status information, time control parameters,or current timing parameters used to perform clock synchronization. 4.The method of claim 1, wherein the store command comprises a store STPinformation command, and wherein the information includes at least oneof a time zone update scheduled indicator to indicate whether a timezone update is scheduled or a leap seconds offset update scheduledindicator to indicate whether a leap seconds offset update is scheduled.5. The method of claim 4, wherein at least one of the time zone updateor the leap seconds offset update is specified by a store time zoneinformation command.
 6. The method of claim 1, wherein the store commandcomprises a store STP information command, and wherein the informationincludes at least one of an indication of a stratum level at a time thestore command was executed, an indication of a coordinated timingnetwork type, an indication of a usable clock source or an indication ofa timing state.
 7. The method of claim 1, wherein the store commandcomprises a store STP information fast command, and wherein theinformation includes at least one of a coordinated timing networkidentifier or timing state.
 8. The method of claim 1, wherein the storecommand comprises a store STP link information command, and wherein theinformation includes link information for one or more links of thecomputing environment that support STP message communication.
 9. Themethod of claim 1, wherein the store command comprises a store STPnetwork node identifier command, and wherein the information includesnode identification information for one or more nodes in the STPnetwork.
 10. The method of claim 1, wherein the command comprises astore time zone information command, and wherein the informationcomprises at least one of time zone control parameters or leap-secondsoffset information.